Semicontinuous vertical lift



June 3, 1969 R. J. MCKNIGHT 3,447,670

SEMICONTINUOUS VERTICAL LIFT Filed May 2, 1967 Sheet of? I NVEN TOR. 455,4 7 AMA M6 June 3, 1969 R. J. M KNIGHT SEMICONTINUOUS VERTICAL LIFT Sheet Filed May 2, 1967 BY M 4rraew s June 3, 1969 Filed May 2, 1967 R. J. M KNIGHT SEMICONTINUOUS VERTICAL LIFT Sheet N TOR.

June 3, 1969 MCKNIGHT 3,447,670

SEMI CONTINUOUS VERTICAL LIFT Filed May 2, 1967 Sheet: 4 of '7 June 3, 1969 R. J. MCKNIGHT 3,447,670

SEMICONTINUOUS VERTI CAL LIFT Filed May 2, 1967 Sh get 6 of 7 June 3, 1969' R. J. M KNIGHT SEMICONTINUOUS VERTICAL LIFT Sheet Filed May 2, 1967 nited States Patent O US. Cl. 198218 16 Claims ABSTRACT OF THE DISCLOSURE A conveyor for transporting articles vertically in either direction having two adjacent tiers of platforms, the tiers being arranged to move in opposite vertical directions simultaneously, producing at one limit of movement, inclined ramps each consisting of two platforms, one belonging to each tier, and at the other limit of movement ramps of the same type but inclined in the opposite direction and consisting of a different pairing of the platforms. The articles are raised or lowered, step by step, as they are transferred back and forth over the inclined ramps. Controls in the form of selectively activated stops and variation in the total vertical movement of the tiers change the conveyors direction of article movement from descending to ascending.

Background of the invention This invention relates to power driven conveyors and more particularly to conveyors for transporting articles vertically rather than generally horizontally or along a sharply inclined plane. The invention transports articles in a step by step manner with the articles when descending being vertically moved partially through the vertical movement of the tiers and partially through the intermittent transfer of the articles by gravity from the platforms of one tier to those of the other. When the conveyor is lifting the articles, movement is accomplished entirely through the vertical travel of the tiers. The invention includes the concept of changing the stroke length of the tiers together with selective use of stops controlling the direction of inclination of the platforms to shift the conveyors operation from one to lower articles to one to lift articles. The invention also includes a platform arrangement permitting high density use of the space occupied by the conveyor.

The basic concept of using a pair of tiltable, inclined platforms functionally related for coordinated operation is disclosed in US. Patent No. 1,034,618. The concept of using a stop to change the angle of inclination of a platform to cause discharge of the articles is found in US. Patent No. 2,522,133.

Summary The invention provides a vertical conveyor of compact cross-section and capable of being designed to any vertical height desired, limited only by the strength of the materials employed. It is basically a self-contained unit capable of permanent installation or of use as portable equipment, movable from one point of demand to another.

It goes further than the structures of the prior patents by providing a single, vertical conveyor capable of reversible operation and of selectively receiving and discharging at any one of a plurality of points between its upper and lower maximum height limits. *It fills a need in the conveyor art by providing a self-contained vertical conveyor of compact cross-section which may be installed in the floor space of a lift but with a significantly higher flow rate capacity than a lift. It is also adapted to the automatic handling of articles of the type normally con- 3,447,670 Patented June 3, 1969 veyed on wheel or roller type conveyors for which most lifts, and bucket type elevators are not particularly adapted. An example of its use in a situation for which other conveyors are not suitable is in loading and unloading ships through a deck cargo hatch of restricted size. In this situation, the entire conveyor can be lowered through the hatch and then removed when the job is done. Thus, a single conveyor unit can serve many ships.

Brief description of drawings FIG. 1 is a side elevation view of a conveyor incorporating this invention;

FIG. 2 is a plan view of the conveyor;

FIG. 3 is a fragmentary sectional 'elevational view taken along the plane III-III of FIG. 2;

FIG. 4 is an end elevation view of one of the cradles used in the conveyor;

FIG. 5 is a fragmentary partially broken oblique view of one of the platforms used in this conveyor;

FIG. 6 is a fragmentary plan view of the platform shown in FIG. 4 when it is aligned with the mating platform of another tier of this conveyor;

FIG. 7 is a fragmentary side elevation view showing the platforms of FIG. 5 in alignment;

FIG. 8 is a fragmentary side view showing the platforms of FIG. 7 as they approach alignment;

FIG. 9 is a schematic side elevation view of the conveyor of this invention in descending phase illustrating the platforms in one position of the cradles in solid lines and in the other position of the cradles in broken lines;

FIG. 10 is a schematic side elevation view of the conveyor in ascending phase showing the platforms in one position of the cradles in solid lines and the other position of the cradles in broken lines;

FIG. 11 is a sectional view of one of the stops taken along the plane XI-XI of FIG. 1;

FIG. 12 is a partially broken side elevation view of one of the platforms equipped with a selective releasing stop;

FIG. 13 is a sectional elevation view taken along the plane XIII-XIII of FIG. 12;

FIG. 14 is a fragmentary section elevation view taken along the plane XIV-XIV of FIG. 12;

FIG. 15 is a schematic side elevation view of a modified form of the conveyor;

FIG. 16 is a schematic diagram of a control system for the conveyor; and

FIG. 17 is a fragmentary view of a gate for regulating the release of articles onto the conveyor; and

FIG. 18 is a schematic illustration of an alternative means of powering the cradles.

Description of the preferred embodiments The numeral 10 refers to a conveyor having a generally box-like frame 11 consisting of four uprights 12, a generally rectangular header 13 and a generally rectangular base 14. It will be recognized that the shape of the header and base, in other words the cross-sectional shape of the conveyor, will depend upon the width and length of the platforms. The header 13 has a pair of cross beams 15 which mount and support the actuating cylinders 16 and 16a.

Within the frame 11 the conveyor has a pair of cradles 20 and 21. Each of the cradles consists of a pair of vertical side beams 22 connected at the top by a header beam 23 and at the bottom by a sill beam 24 (FIG. 4). Each cradle has a plurality of platforms 25 arranged at spaced a unit having six platforms is merely exemplary, it being possible to construct a conveyor in accordance with this invention with a greater or a lesser number of platforms. In the embodiment shown in FIG. 1 each of the cradles has the same number of platforms 25, although this is not necessarily true in all embodiments of this invention.

Each of the platforms 25 is biased to an inclined position with its outer end sloped downwardly in the manner of the platforms of cradle 21 as illustrated in FIG. 1. This bias is imparted by a pair of springs 27, which pivot the platform until it is limited by the stop 28 (FIGS. 1 and 4).

Each of the cradles at its lower end is stabilized by a pair of guide tracks 29, one on each side, which slidably engaged a dog 30 projecting from the sides of the cradles (FIG. 4). At the upper end the cradles are stabilized by a pair of guides 31 within which slide the dogs 32 projecting from the sides of the cradles. The cradles are tied together at their lower ends by a rocker beam 33 pivoted at its center on the shaft 34 secured to the side bars 35. At is upper end cradle 20 is secured to a piston 36 and cradle 21 to a piston 36a. The pistons and cradles are vertically reciprocated by the cylinders 16 or 16a.

To clarify the description of the more sophisticated aspects of this invention, the operation of an elementary form of the conveyor will be described. For this purpose, reference is made to FIGS. 1 and 9 and particularly to FIG. 9 which illustrates the conveyor operated in descending phase, that is, to lower articles.

Each of the cradles and 21 can be considered a tier of platforms 25. For the sake of clarity, the platforms of the cradle or tier 20 are numbered through 25c, from top bottom, and the platforms of the cradle or tier 21 are numbered 25 through 25k, top to bottom. The operation of the cylinders 16 and 16a is synchronized with the cylinders operating simultaneously in opposite direc tions. That is, when the piston 36 is advancing the piston 36a is retracting. Thus, the cradles 20 and 21 reciprocate in opposite directions at the same time. Activation may be accomplished in several ways. For example, in FIG. 18 the cradles 20 and 21 may be joined by one or more cables 94 passing over pulleys 95. The cables are reciprocated by the piston and cylinder assembly 96.

In FIG. 9, the cradle 20 is shown in solid lines at the lower limit of its travel while the cradle 21 is shown in solid lines at the upper limit of its travel. It will be noted that, as illustrated in FIG. 9, all of the platforms except platforms 25e and 25 are inclined downwardly to the left and all of the platforms except platforms 25c and 25] are arranged in pairs, forming a continuous inclined slope from one end of the conveyor to the other end. In this arrangement, it will be noted that the following platforms form pairs with each pair being a ramp; platforms 25 and 25g; platforms 25a and 25h; platforms 25b and 251'; platforms 25c and 25 platforms 25d and 25k forming the bottom pair. When the conveyor is in this condition, all of the articles on the platforms 25, 25a, 25b, 25c and 25d will, by gravity, shift to the left and come to rest at the left end of the platforms 25g, 25h, 25i, 251' and 25k respectively. They are restrained against further travel by stop mechanisms at the left ends of these platforms, which stop mechanisms will be described subsequently.

Platform 25 will be inclined to the right and is aligned with a supply conveyor 40 at the top of the vertical conveyor 10. As so positioned and inclined it receives one or more articles from the supply conveyor 40. The platform 25c is also inclined to the right and is aligned with the discharge conveyor 41. As so positioned and inclined it will discharge its articles.

At this point the pistons 36 and 36a reverse directions, raising the cradle 20 and lowering the cradle 21. When the cradles reach the limit of this movement, that is, when the cradle 20 reaches the upper limit of its travel and the cradle 21 reaches the lower limit of its travel, the platforms will be rearranged as indicated in broken lines in FIG. 9. In this arrangement, the following pairs of platforms will be aligned as ramps: platforms 25 and 25 25a and 25g; 25b and 2511; 25c and 251'; 25d and 25 2512 and 25k. The paired platforms will now be inclined oppositely, that is, to the right. Now, articles at the left hand end of each of the platform pairs or ramps will be transferred to the right hand end of the platform pairs and are restrained against further travel by stop mechanisms at the right hand ends of these platforms. One such stop arrangement suitable for this purpose is illustrated in FIGS. 12 and 13. It will be seen from the above description that the articles on the conveyor illustrated in FIG. 9 will move down the conveyor, step-bystep, from the supply conveyor 40 to the discharge conveyor 41. Under full load, each of the platform pairs will have, at least, one article on it.

As has been explained earlier, each of the platforms is biased by its spring 27 to be inclined downwardly toward its outer end, that is, the platforms of cradle 20 to the right and the platforms of cradle 21 to the left. To incline the platform the opposite way, stops 42 are provided on the uprights 12 to engage beneath the outer ends or other suitable portions of the platforms as the platforms descend. The stops hold the outer ends of the platforms stationary, causing the platforms to reverse their direction of inclination about their pivots 26 as the cradle continues its descent. On the right hand side of FIG. 9 the stops 42, 42a, 42b, 42c, and 42d effect the reverse tilting of the platforms 25, 25a, 25b, 25c, and 25d respectively. On the left hand side of the platform the stops 42f, 42g, 42h, 421', 42 and 42, effect reversal of the angle of inclination of the platforms 251, 25g, 25h, 251', 251' and 25k respectively. When the cradle 21 is in up position, the cradle platform 25 is inclined to the right by the stop 39 mounted on one of the side bars 35 (FIG. 1).

The preceding description with relation to FIG. 9 covers the operation of the conveyor when it is used to lower articles. FIG. 10 illustrates the operation of the conveyor when it is used to elevate articles, that is, in

ascending phase. This may be accomplished using the' same conveyor, cradle and platform arrangement. In the lowering operation, the transfer of the articles from one platform to another is effected by the downward inclination of the platform pairs. Thus, the articles are moving downwardly at all times. However, when the conveyor is used to elevate, some distance gained due to the stroke of the cradles is lost as the articles are transferred from right to left and left to right as they shift from one platform to another. This loss is compensated by increasing the length of the stroke of the cradles 20 and 21 whereby they move further down to reach their lower limit and further up to reach their upper limit. This arrangement is illustrated in FIG. 10. In this figure the same platform numbering as that used in FIG. 9 is retained, permitting the differences in operation to be clearly understood.

The articles are initially received by the platform 252 from the supply conveyor 44 at the bottom of the vertical conveyor. When the cradles reverse their position, the platform 25c rises to the position illustrated in broken lines where it is paired with platform 25k and transfers its articles to platform 25k. On the next stroke reversal the platform 25k rises to form a pair with the lowered paltform 25d and the article is transferred to the latter platform (illustrated in solid lines). Thus, in step-bystep fashion, the articles are moved up the conveyor until they finally reach platform 25], from which they are discharged onto the discharge conveyor 45. Release from the platform is effected by the stop e as subsequently described.

To incline the the receiving platform 25c downwardly to the left as illustrated in FIG. 10, a stop is provided. To incline the platforms 25g, 25h, 251', 25 and 25k downwardly to the right, as illustrated in solid lines in FIG. 10, stops 46, 46a, 46b, 46c and 46d are provided adjacent the right hand ends of these platforms. When the platforms are shifted to the position illustrated in broken lines in FIG. 10, the platforms 25, 25a, 25b, 25c, 25d and 25e are inclined downwardly to the left. This is accomplished by means of the stops 47, 47a, 47b, 47c, 47d and 47.2. These stops along with stops 46, 46a, 46b, 46c and 46d are mounted on the side bar 35 (illustrated in FIG. lomitted from FIGS. 9 and 10 for clarity) and engage the inner end of these platforms to cause the inclination reversal.

It will be noted from FIG. 9 that the stops 47 through 47e and 46 through 46d are so positioned that they do not interfere with the platforms when the conveyor is operated in descending phase as the conveyor is illustrated in FIGS. 1, 9 and 10. This is the result of the increased stroke length required when the conveyor operates in ascending phase. Thus, they need not be retracted. This is not true when the conveyor is constructed as illustrated in FIG. 15. However, it will be noted that the same is not true of the stops 42 through 42k. Accordingly, these stops must be retracted when the conveyor is to be operated in ascending phase. One arrangement for carrying out the retraction of the stops is illustrated in FIG. 11. In this figure stop 42 is illustrated as having a stop pin 48 projecting through one of the uprights 12 and powered by any suitable means such as a solenoid 49. When the stop is not to be utilized the stop pin 48 is retracted by activating the solenoid. It will be recognized that any other suitable power source for reciprocating the stop pin 48 may be used such as pneumatic or hydraulic. It will be recognized that the stops can be so constructed that their normal positions are either advanced or retracted.

The length of the stroke of the pistons 36 and 36a powering the cradles and 21 may also be regulated by suitable stops. As is suggested in FIGS. 1 and 4, a suitable finger 50 is provided at one side of the header beam 23 and a second stop 51 is provided on the opposite side (FIG. 4). The stop 50 is designed to engage the micro-switches 52 and 53. The micro-switch 52 serves as a lower unit control and the micro-switch 53 serves as an upper limit control when the conveyor is operating in descending phase. When the conveyor is operating in ascending phase, the micro-switches 52 and 53 are retracted by the solenoids 54, permitting the cradles to travel within the limits of the switches 55 and 56. These switches are tripped by the stop 51. Again, it will be recognized that appropriate pneumatic or hydraulic valves can be substituted for the switches 52, 53, 55, and 56 if controls of this type are desired, also the retraction of the switches or valves 52 and 53 may be effected by hydraulic or pneumatic cylinders rather than the solenoids 54. The signals generated by the limit switches 52, 53, 55 and 56 regulate the operation of a solenoid actuated valve 98 through the double operating switch 99 (FIG. 16). The valve 98 controls the flow of fluids to the cylinders 16 and 16a.

In a situation such as that of the platform when the conveyor is in descending phase, it may be desirable to provide a stop at the inner end of the platform to prevent the articles from over-traveling the platform before the platform 25 f is paired with the platform 25. One way of accomplishing this is shown in FIGS. 6, 7 and 8. In this arrangement, a pivoted stop 60 is provided at the inner end of platform 25f consisting of a stop bar 61 pivoted on one of the axles 62 of the platform and equipped with a combination trip bar and counterweight 63 which normally holds the stop bar 61 in erected position to restrain the movement of articles beyond the end of the platform. The platform 25 has a trip arm 66 designed to engage beneath the trip bar 63 as the platforms move into alignment. As the platform 25 rises into paired relationship with the platform 25 the trip arm 66 engaging the finger 64 will depress the stop bar 61, permitting the article to shift from platform 25f to the platform 25.

It will be recognized that other stop arrangements may be utilized to effect the same purpose and that the specific mechanism described is merely illustrative of the various mechanisms which may be utilized.

A substantially more sophisticated conveyorcan be developed from the one already described by making the conveyor capable of either receiving or of discharging at any one of the many levels which represent the intermediate stages between the conveyors upper and lower ends. This can be done whether the conveyor is in ascending or descending phase. For example in FIG. 9 assuming the platforms to be in the positive illustrated in solid lines, it would be possible to provide a suitable discharge conveyor aligned with the left hand end of each platforms 25g, 2511, 251', 25 and 25k. It is also possible to provide similar discharge conveyor means to receive articles from the right hand ends of platforms 25a, 25b, 25c, and 25d in addition to the discharge conveyor 41 if these conveyors are aligned with the right hand ends of the plaforms as they are shown in broken lines in FIG. 9. In the samemanner, it is possible to discharge to the right from the platforms 25, 25a, 25b, 25c, and 25d when the conveyor is in ascending phase as these platforms are illustrated in solid lines in FIG. 10. Discharge could be effected from the left hand ends of the platforms 25f, 25g, 25b, 25:, 25 and 25k in ascending phase, when these platforms are in the positions shown in broken lines in FIG. 1.

To do this, it is necessary to provide suitable article stops on certain of the platforms which stops are tripped when discharge is to occur. A possible arrangement for accomplishing this is illustrated in FIGS. 12, 13, and 14. For purposes of illustration, it is assumed that the platform illustrated in FIG. 12 is platform 25 and discharge would occur at the right hand end, as illustrated. It will be seen that at its right hand end the platform has a stop 70 projecting upwardly into the path of articles on the platform. The stop 70 is adjacent one end of a rocker frame 71 pivotally mounted adjacent its center on the axle 72. The outer end of the rocker frame projects beyond the end of platform and is equipped with a trip bar 73. A pair of springs 74 normally hold the stop member 70 in erected position.

The rocker frame 71 extends almost to the other end of the platform 25 and at this end has a trip finger 75 projecting beneath the platform. This trip finger is designed to engage the stop 80, when the stop is extended (FIGS. 10, 12 and 14). The stop is mounted on the side bar 35, opposite from the side bar mounting the stops 47 through 47s.

It will be seen that as the platform 25 descends from its upper limit of travel (indicated in broken lines in FIG. 10 to the lower limit of its travel where is is paired with the platform 25g, the stop 80 if extended will engage the trip finger 15, rocking the inner end of the rocker frame 71 upwardly retracting the stop 70. This allows the article on platform 25g to move across platform 25 and off the conveyor onto a suitable discharge conveyor line. Similarly the same results may be obtained by the same mechanism with respect to the platforms 25a, 25b, 25c, and 25d. To effect these purposes, in addition to stop 80, stops 80a, 80b, 80c, and 80d are provided.

If the discharge is to occur to the left When the platforms 25 through 25k are in the position illustrated in broken lines in FIG. 10, the release from these platforms will be effected in a similar manner by extension of any one of the stops 81 through 81c. These stops are individually and selectively actuated. Any of the stops 80 through 80d and 81 to 81c which is not to be utilized, is retracted. The retracted stops do not engage the trip fingers 75 of those particular platforms.

When the conveyor is used in descending phase, all platforms move upwardly to their receiving positions. Thus, for example, the platforms 25f through 25k move upwardly to the positions illustrated in solid lines in FIG.

7 9 and the platforms 25 through 25? also shift upwardly for the same purpose as illustrated in broken lines. The platforms 25 through 25k shift downwardly to their discharge positions as illustrated in broken lines in 'FIG. 9 and the platforms 25 through 252 shift downwardly for the same purpose, as illustrated in solid lines. This re quires a different type of stop to trip the stop bar 70. In this case, stops 84 through 842 are provided for the platforms 25 through 252 respectively, and stops 85 85d are provided for the platforms 255 through 25k respectively. These stops, when extended, engage the trip bar 73 from above. Since the platform is moving up- W-ardly the stops pull the stop arm 70 downwardly to retracted position. The stops 84 through 8442 and 85 through 85d are retractible permitting them to be withdrawn or retracted when they are not to be used.

When the conveyor is in ascending phase and it is desired to take the articles to the limit of upward travel, an additional stop 852 is provided to cooperate with the platform 25f on the left hand side, at the top of the conveyor (FIG. 10) to retract a gate of the type illustrated in FIGS. 12 and 13. Stop 8Se is also retractible.

As will be pointed out in connection with the description of the controls for this conveyor, it is possible to operate selectively and manually either singularly or in groups the stops 80 through 80d, 81 through 81a, 84 through 84a, and 85 through 8512 to effect selective discharge at any point up and down the conveyor. This can also be done automatically by signals read off the articles themselevs. It can be done by programming through a counter which will automatically discharge at any one of the levels in accordance with pre-programmed selection. An example of a use of this conveyor with selective receiving and discharge at any point along the conveyor would be its use to service vertically tiered storage racks. The conveyor can then be used both for moving articles into storage and for withdrawing them.

FIG. 16 schematically illustrates one system of controls suitable for this conveyor. The numeral 100 indicates a main power source. By manipulation of the switch 101 to close the circuit 115 to the control panel 102 the system can be operated through the control panel 102 for automatic selective receiving and discharge at any level or operated automatically simply to raise and lower articles between a single upper and single lower limit. If non-selective receiving and discharge is desired the switch 101 is moved to close either of the circuit 117 or 118. As illustrated, if the switch 101 is closed to circuit 117, the conveyor will operate in descending phase because the stops 42 through 42k will be activated. If the switch 101 is closed to circuit 118, the conveyor will operate in ascending phase since the stops 45, 46 through 46d and 47 through 47c will be activated. Selection of descending phase by closing of circuit 117 will activate the solenoids 54 shifting the limit switches 52 and 53 into operative position. If ascending phase is selected by closing the circuit 118, the solenoids -4 will be deactivated retracting the limit switches 52 and 53. This permits the limit switches 55 and 56 to control the stroke length of the pistons 36 and 36a.

If on the other hand the conveyor is to be utilized to receive or discharge at any of a number of selected levels, the switch 101 is moved to close circuit 115. The control panel may be so designed that the information necessary to control the receipt and discharge of articles at various levels can be fed into the control panel by an operator, item by item. It may also be of the type wherein some type of signal generating device provided on or associated with the article is passed on to one of the counters 104 and 105. The counter then effects the discharge of the article in accordance with this information, generally in association with other pre-programmed information fed to the counter from the control panel 102. It is also possible to pre-program the entire system to receive and discharge articles in accordance with a 8 predetermined article selection and handling plane. In accordance with the signals generated at the control panel 102, either the counter 104 or the counter 105 is activated. The counter 104 controls receiving and discharge when the conveyor is in descending phase. The counter 105 controls receiving and discharge when the conveyor is in ascending phase. It will be observed that the selector 106 controlling the descending phase, manipulates the stops 85 through 85d together with the stops 84 through 842. In similar manner, the selector also controls the individual gates which regulate the release of articles from the conveyor at each of the various levels. The necessary article supply lines are schematically shown in FIG. 1 and are identified by the numerals 111 through 111k. Each of these supply lines is equipped with a stop. These stops are numbered 110 through 110k in FIG. 1. Each of these stops is individually connected to the selector 106 through the cable 119 (FIG. 16).

Selector 107 controls the ascending phase of the conveyor when the control panel is operative. This selector controls stops through 80d, 81 through 81:; and e. In addition, the selector 107 controls a group of stops or gates on the various supply lines at the multiple levels at which the conveyor can receive articles. These stops are schematically suggested in FIG. 16- and identified by the numbers 112 through 112k and are individually connected to the selector 107 by the cable 108. To avoid overcrowding of the drawings, the stops 112- 112k are not illustrated in FIGS. 1, 9 and 10. However, it will be under-stood that the arrangement would be generally similar to the gates or stops numbered 110 through 110k.

Control of the actuation of the cylinders 16 and 16a is schematically illustrated in the upper right corner of FIG. 16. Switches 53 and 56 are both connected to the solenoid 201. Switches 52 and 55 are connected to another solenoid 202. Both solenoids 201 and 202 are connected to the switch 203 which regulates the operation of the solenoid operated valve 204. When the switch 203 is biased to the left the valve will cause the cylinders 16 and 16a to operate in one direction and when the switch 203 is biased to the right the cylinders will operate in the opposite direction. The supply 205 of air or hydraulics for the cylinders passes through the valve 204 and the lines 206a, b, c, and d to the cylinders 16 and 16a.

The switch 203 is biased to a neutral position by 'a. spring 207 when both solenoids 201 and 202 are inoperative. When this occurs, both lines 208 and 208a are open. Both of these lines are connected to a main shut-off valve 209 in the main supply line. This valve is so designed that it automatically closes if both lines 208 and 208a are open. The closing of valve 205 shuts down the power source for the machine.

It will be recognized that the preceding description of a control system for this conveyor is merely illustrative since various other arrangements electronic hydraulic or pneumatic or mixtures of these various motive systems can be used to regulate the operation of the conveyor.

While FIG. 1 shows the gates 110* through 110k as mounted on the supply conveyors 111 through 111k respectively, it will be recognized that these gates can be mounted on the conveyor itself rather than on the supply conveyors. Such an arrangement is suggested in FIG. 17 wherein the gate 110 consists of a central folding linkage supported on one end by a stationary bar 141 fixed to one of the uprights 12 and on the other end by the movable bar 142. The movable bar 142 is supported for horizontal sliding movement on an opposite upright 12 by the guide 143 and is reciprocated by the solenoid 144. This gate is seated between the ends of the supply conveyor 111 and the platform 25. When the solenoid is retracted, the gate is lowered and articles can pass from the supply conveyor to the platform. When the solenoid is extended, the folding linkage rises to block article movement. It will be recognized that this gate structure is merely illustrative and numerous other well known gate mechanisms could be substituted for it.

It is also possible to use the empty platform method of controlling the receipt and discharge of articles. For example, articles on a platform could interrupt an appropriately located light beam at each level. Absence of an article could generate a signal which would automatically open the appropriate supply line gate to load the empty platform.

Although it was pointed out earlier in this description that stops 47 through 47:: need not be retracted when the conveyor is shifted from ascending to descending phase, FIG. 16 shows them as retractible. This becomes necessary when the conveyors capacity is doubled in the manner suggested in FIG. and about to be described.

FIG. 15 illustrates this invention with a conveyor of the same vertical height as that illustrated in FIG. 1 but with twice the capacity. This is accomplished by doubling the number of platforms. Thus, cradle 20, in addition to the platforms 25 through 25a, also has platforms 120 through 120e and cradle 21 in addition to the platforms 25 through 25k has platforms 120 through 120k. In this arrangement, when the cradles 20 and 21 are in the respective positions illustrated in solid lines and operating in descending phase, the conveyor receives articles from the supply conveyor 130 onto the platform 25 Simultaneously, the article on platform 120 is transferred to platform 120g. When the cradles reverse their position to that illustrated in broken lines in FIG. 15, the platform 120 receives an article from the supply conveyor 131. Simultaneously, the platform 25 discharges its article to platform 25. Thus the conveyor receives an article at the end of each stroke, rather than at the end of each alternate stroke.

At the lower end, when the cradle 20 is in its lowered position (solid lines), the platform 25e discharges onto the conveyor 132. When the cradles are reversed (broken lines), the platform 25:: is aligned with platform 25k. At the same time the platform pair 120k and 1202 are aligned with the discharge conveyor 133 and the article on platform 120k discharges from the conveyor across platform 1202. Thus article discharge occurs at each l1m1t of cradle travel. It will be recognized that the basic function of this modified conveyor is identical to that of the conveyors shown in FIGS. 1 and 9. It will also be recognized that by changing the stroke length of the cradles 20 and 21, the conveyor illustrated in FIG. 15 can be utilized for elevating articles and in the same manner as it functions in descending phase, the capacity of the conveyor will be doubled. It will also be recognized that the same basic control systems as that already illustrated and described in connection with FIG. 16 can be applied to the conveyor shown in FIG. 15, although the number of stops will be doubled. The doubling of these stops is, however, merely an engineering undertaking, once the basic system illustrated in FIG. 16 has been taught and described.

Having illustrated and described preferred embodiments of this invention, it will be recognized that various modifications of the invention may be made, each of which will embody the basic principles set out above.

I claim: I

1. A vertical conveyor having a plurality of platforms arranged at equally spaced intervals in two adjacent vertical tiers; all of the platforms of each tier being pivotally mounted on a cradle and means for vertically reciprocating said cradles simultaneously in opposite vertical d1rections; at one limit of vertical travel of said cradles, said platforms forming inclined ramps each consisting of a pair of platforms; at the opposite limit of vertical travel of said cradles said platforms forming ramps inclined 1n the opposite direction, each ramp consisting of a pair of platforms with one platform of each pair being different from the platform which formed a ramp with other platforms when said cradles were at said one limit of travel,

the conveyor being characterized in that each of said platforms is biased to an inclined position with all of the platforms mounted on one of said cradles inclined in one direction and all of the platforms on the other of said cradles inclined in the opposite direction, said inclination of said platforms under said bias being downwardly away from each other; stationary first means engaging the platforms to change the direction of inclination of said platforms when said cradles are at opposite limits of their travel.

2. A vertical conveyor as described in claim 1 wherein springs are provided to bias each of said platforms.

3. A vertical conveyor as described in claim 1 wherein second means are provided to change the distance of vertical travel of said cradles for changing the direction of vertical travel of articles on said conveyor.

4. A vertical conveyor as described in claim 3 wherein third means are provided to reverse the angle of inclination of said ramps formed by said platforms when the direction of vertical travel of articles on said conveyor is changed.

5. A vertical conveyor as described in claim 4 wherein said first and third means are stops engaging said platforms adjacent one of their ends for restraining vertical movement of the engaged end of the plat-form to pivot the platform about its pivotal attachment to its cradle as the cradle moves vertically.

6. A vertical conveyor as described in claim 5 wherein said stops are shiftable between extended and retracted positions and engage said platforms only when in one of said positions.

7. A conveyor as described in claim 6 wherein a control unit is provided, said control unit being connected to each of said stops and said means for changing the distance of vertical travel of said cradles for coordinating the operation thereof.

8. A vertical conveyor of the platform type having a frame; a plurality of platforms arranged at equally spaced intervals in two vertical tiers, said tiers being in end to end relationship; each of said platforms having an inner and outer end, with the inner ends of the platforms being directed toward each other; a pair of cradles, one for each of said tiers of platforms and means to reciprocate said cradles vertically and simultaneously in opposite directions; each of said cradles having a pair of spaced vertical members; said platforms of each tier being pivotally mounted to and between said members at a point adjacent the midpoint between the ends of said cradles; the improvement in said conveyor comprising: said vertical members being the sole support for said platforms; a spring biasing each of said platforms into an attitude inclined downw ardly toward the outer end of the platform under the bias of said spring; said cradles being mounted for reciprocating vertical movement and means connecting them together for simultaneous movement in opposite directions; stop members on said frame positioned to engage said platforms when their cradle moves downwardly; said stop members engaging the outer ends of said platforms for reversing their angle of inclination when said platforms are at the lower limit of their travel; said platforms at one limit of their travel being aligned and inclined in one direction and at the opposite limit of their travel being aligned and inclined in the opposite direction.

9. A vertical conveyor as described in claim 8 wherein said conveyor has a supply track aligned with the uppermost of said platforms on one of said cradles when said platform is at the upper limit of its travel and inclined downwardly away from said supply track; a discharge track aligned with the bottom platform on the other of said cradles when said other cradle is at its lower limit of travel and inclined downwardly toward said discharge track.

10. A vertical conveyor as described in claim 8 where- 11 in a control element is provided to limit the vertica travel of said cradles.

11. A vertical conveyor as described in claim 10 Wherein means are provided to change the length of vertical travel of said cradles for reversing the direction of vertical movement of articles by said conveyor.

12. A vertical conveyor as described in claim 11 wherein cradle engaging members are provided at vertically spaced intervals to reverse the direction of inclination of said platforms when the direction of movement of articles by said conveyor is changed.

13. A vertical conveyor as described in claim 11 wherein a gate is mounted on each of said platforms for preventing the movement of articles off the outer ends of said platforms and first control members for selectively opening each of said gates to permit the discharge of articles from the platforms; said first control members being operative when said conveyor is moving articles downwardly; second control members for selectively opening each of said gates to permit the discharge of articles from the platforms operative when said conveyor is moving articles upwardly.

14. A vertical conveyor as described in claim 13 wherein receiving gates are provided one for each of said platforms except one; third control members for selectively opening each of said receiving gates to permit the entry of articles onto said platforms.

15. A vertical conveyor as described in claim 14 wherein cradle engaging members are provided at vertically spaced intervals to reverse the direction of inclination of said platforms when the direction of movement of articles by said conveyor is changed; a coordination unit connected to each of said cradle engaging members, first, second and third control members and means for changing the length of cradle travel for coordinating the operation thereof.

16. A vertical conveyor as described in claim 8 wherein a gate is mounted on each of said platforms for preventing the movement of articles off the outer ends of said platforms and first control members for selectively I opening each of said gates to permit the discharge of articles from the platforms.

References Cited UNITED STATES PATENTS 93,373 8/1869 Van Dyk 198218 500,344 6/1893 Moore l982l8 698,933 4/1902 Gould l98218 1,361,445 12/1920 Comstock 198-218 X FOREIGN PATENTS 144,730 4/ 1931 Switzerland.

RICHARD E. AEGERTER, Primary Examiner. 

